1. Field of the Invention
The present invention relates to a mechanism for supporting transmission shafts in an automatic transmission apparatus.
2. Description of the Prior Art
Automatic transmission apparatus for vehicles have many transmission shafts such as an input shaft, output shaft and intermediate shafts between the input and output shafts. Usually, these transmission shafts are rotatably supported at their both ends.
When the span of support of a transmission shaft is large, or when a load is applied to a mid portion between two supporting points, the transmission shaft tends to be deflected and oscillated at the mid portion thereof. This in turn causes a vibration such as to abnormally load the transmission apparatus, resulting in a deterioration of the durability of the transmission apparatus.
This type of automatic transmission apparatus usually has an automatic transmission case which is constituted by a torque converter housing accommodating the hydraulic transmission unit and an extension housing fixed to the output side, i.e., the rear end, of the transmission case. Usually, each transmission shaft is supported rotatably at two points thereof on an automatic transmission case.
In the conventional automatic transmission apparatus of the type described, the output shaft is supported at its mid portion and the output end or rear end portion thereof by the rear end portion of the transmission case and by the rear end portion of the extension housing, respectively, while the input-side end of the output shaft is unsupported. The present inventors have found that, as a result of current trends for large engine output power and, hence, an increase of the torque to be transmitted, the unsupported input-side end portion of the output shaft tends to be oscillated particularly when the span of support is large or when load imposed on the output shaft acts in the direction perpendicular to the axis of the same at a portion between two supporting points, which in turn causes a large vibration and a consequent abnormal load on the transmission, resulting in a deterioration of durability of the automatic transmission apparatus.